Oral care compositions such as dentifrices typically contain dentally acceptable abrasive, humectant, water, and water-soluble polymer which serves as a thickener and binder for the ingredients. A variety of other ingredients such as flavours, sweeteners, preservatives and fluoride are also utilized at low levels.
However there are many materials which are physically or chemically incompatible with the aqueous environments found in typical dentifrice formulations.
Non-aqueous formulations have been suggested as a way of improving the stability of these materials. For example, WO96/03108 describes a non-aqueous dentifrice composition comprising a carboxyvinyl polymer, a humectant, a polyethylene glycol and a dentally acceptable abrasive. The carboxyvinyl polymer is stated to thicken the humectant materials and provide the necessary rheology in order to suspend any required abrasive material. A polyethylene glycol selected from PEG 300 and PEG 400 is stated to reduce stickiness from the formulation and give a smooth textured product.
A problem with non-aqueous formulations such as those disclosed in WO96/03108 is that they do not behave rheologically like a typical aqueous dentifrice. This problem is observed both during manufacture and during use by the consumer. It has led to manufacturing difficulties and reduced acceptance amongst consumers. Viscosity profile and flow characteristics are key factors governing ease of processing, product performance and consumer perception of a dentifrice.
The present inventors have found that this problem can be solved by the incorporation of a particular combination of polyethylene glycols.